Wacker: handling the waste stream

I was invited to spend some time at Wacker, and yesterday we went on a plant tour of the firm’s production site in Burghausen, about an hour outside of Munich. The site is very large – about 2.3 square kilometers, and almost 10,000 people work there. At the site, Wacker makes polysilicon wafers for the semiconductor industry as well as pure polysilicon for solar modules, among other products like silicones and polymers.

The four main input raw materials for the site are metallurgical silicon, methanol, ethylene and rock salt. One of the more detailed stops of the plant tour was the area where the waste is handled.

Compared to the size of the plant, there did not appear to be a great deal of waste to dispose of. The main reason is that Burghausen is a very integrated site; waste from one process is used as input to another. A small area held a number of plastic and metal drums, all labeled with the specific type of waste (the facility handles solid, liquid and gas wastes – gas comes through a pipe system). Wacker tracks each container of waste from its generation point to its disposal. Nothing is lost.

The waste is incinerated, along with the container which gets chopped up into tiny pieces. All the incineration gases are trapped and scrubbed. Any rocks or metal slag resulting from the burn is stored in a landfill and later the metal is recovered and recycled. Steam heat from the incineration is used to turn a turbine and contribute power to the plant. The gases from the incineration are run through a catalytic scrubber, and the resulting waste stream is monitored on a half-hour average basis with data tracked by a third party company that reports to Germany’s environmental regulator. Every year, Wacker has to publish a public report about its emissions.

Other than a little steam coming from the top of an exhaust tower, there was no other sign of any molecules leaving the facility.

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The Safety Zone covers chemical safety issues in academic and industrial research labs and in manufacturing. It is intended to be a forum for exchange and discussion of lab and plant safety and accident information without the fanfare of a news article.